DE1541951A1 - Locking circuit for electrical equipment - Google Patents

Description

PATS »TANWAI.I,. ing. R. HOLZEB

RO A IT G S B U It G

VELS ER-STBASSB IA ■ r * N. SMtI

M.

Augsburg, June 26, 196?

National Research Development Corporation, Kingsgate House, 66-74 Victoria Street, London S.W.1, England

Lock-out circuit for electrical equipment

The invention relates to blocking circuits which are used in lines or connections of electrical devices Attenuation of undesired short-term voltages or radio frequency interference signals can be used, the latter being Spread along these lines or connections.

Known devices for reducing the short-term voltages or radio waves caused by such undesirable

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Effects caused by interference signals have the disadvantage that they are cumbersome and tend to reflect the unwanted signals back and forth along the connection lines.

By means of a low-pass filter, unwanted radio frequency signals can be blocked and sudden, short-term voltages can be grounded at a high level . Up to now, it has been considered desirable to use filters whose elements are essentially made up of pure blind levels exist as far as this is economically possible in order to avoid any unnecessary power loss means used, not operate satisfactorily with lossy filters, while it is useless in connection with another device or sogrr disadvantageous addition, a simple filter tends to reflect the blocked by it signals so dc B along the ITetzanschlußleitungen and other compounds Hike back and forth Effects caused by these unwanted signals tend to change accordingly

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to repeat and / or expand these reflections.

Through the invention; should the task be resolved, in the case of devices for the attenuation of undesired, short-term Voltages and redio frequency interference compact design, reliable and powerful 7 / effective with relatively low reflection "at the energy conversion to achieve.

Furthermore, the object is to be achieved by such Blocking circles jleich- and iriederfremenzverrorijunc-sströrne to get through dissipation losses can.

In the sense of dex * solution of this on; ^r be ro: "."¹; The invention of a blocking element eii.ea Tiefp- ι-Γϋΐ; ο. / ε 'iU3, in which at least one HnIflied is an inductive series input. Sin derrrti ^ er locking circuit is'-enis'I? the invention by gskeTin ^ oiohnet, ä ".." sr Goeinleitvrert the inductive 3-rrieninr ^ d ^ nz a '..ii-kl.2itv, -ert ^r part of at least the. "- leicken Sri' ¹ " · ? ::: _Jnun ^ v: ie the reciprocal of the FiltGr-Wellenvridorst-'r.: ": - 3 '■: i: il ^ ;.

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The reciprocal of the wave resistance is the optimal one V / ert for the conductance of the impedance of the end link. According to the invention, the Y / irkleitwert is preferably in Range between half and double the V / ert of the reciprocal value of the filter wave impedance.

A simple embodiment of the invention can be a T-element low-pass filter with inductive series branches and, as the trunk of the T-element, with a shunt capacitance. According to the invention, the inductive series branch remote from the source of the noise or interference signals to be suppressed consists of an inductance and a resistor connected in parallel to this, while the inductive series branch facing the noise or interference signal source consists of a simple inductance. If, according to the invention, the inductances are the same and each have an inductance of Lyu.il and the capacitance a size of 23 ju.1 , then the optimal V / ert for the resistance is equal to the characteristic impedance / L / C of the filter .

To get greater attenuation, two or more! - links of the type described above behind-

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are interconnected. The individual links can be selected so that they together form a bandpass filter

j.

form. Have several consecutive T-GI eders, however, if the characteristic impedance is approximately the same, the limit frequencies will increase. Other embodiments of the invention may comprise combinations of one or more known filters or of such be derived, which with one or more T-members connected in series of the type previously described are. The end of the filter remote from the noise source should always have an inductive series impedance with a conductance of the same size as the characteristic impedance of the filter. Where required is to attenuate noise signals passing through the filter in both directions, both ends of the filter can be used each have an inductive series impedance with a suitable conductance.

The inductive Series impedances each know from an induction coil exist, to which an additional resistor is connected in parallel, but this is not required is. An induction coil can be constructed in such a way that

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BATH ORIGINAL

that it already has a shunt conductance, for example by being in the immediate vicinity of their winding Radiofrequency dissipation material is attached. That Radiofrequency dissipation material can consist of any resistance material, but which is preferably is arranged so that it exerts significant dissipation on interfering radio frequency signals, while it is on direct current and low-frequency mains connections has relatively little or no dissipation at all. Such a frequency-dependent one Dissipation can be achieved in several ways, e.g. due to the presence of electrical resistance material at or near the surface of the induction coil, through the induction of eddy currents in the electrical resistance material, through the use of material with dielectric or magnetic I ^ steresis losses, through the use of dissipative dielectrics, through the use of magnetostrictive or piezoelectric Devices for the dissipation of electrical energy by means of mechanical vibrations, by a capacitive connection to a dissipation element or by any combination of such arrangements. The dissipation material can take the form of a dissipation

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core, "for example of a conductive ferrite, which also increases the inductance. The dissipation material can be any, for Cores of induction coils have a commonly used shape.

Where the end links of the filter have a freedom-dependent conductance, the aforementioned loit and resistance values should correspond to the conductance and resistance values as measured at the noise and / or interference frequencies to be suppressed. Through the interference blocker described above, direct and low-frequency network currents can flow through in each direction with only slight dissipation losses, since these interfering currents tend to endeavor, if possible only through the inductive part and not through the dissipative part -the final link ex ^{1 to} let through. Such blocking circles baw. Are sturgeon can lock both in connection :: iit Signnlleitongsverbindungen · Is in Verbindimg with ITetsrnschlu.'ileitungen verv / ends.

When turning traps or interference barriers is with the previously mentioned filters

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8AD ORIGINAL

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The main disadvantage of pure reactances as terminal links is that they are used elsewhere, but with the same Input and output lines connected devices in the filter interact with reactive elements and resonance effects can occur as a result, which completely destroy the effect of the filter or even amplify the disturbances instead of suppressing them.

The use of a sufficiently dissipative end link or end links, as described, reduces the possible effects of such interactions and dampens any reflection that may still occur. The blocking circuit according to the invention has an attenuation of at least oC «20 log (G _ßC | Z _m |) decibels with respect to each interference frequency f, where Gg ~ the short-circuit conduction

v / ert and | Ζ ~ | the coupling resistance or the transmission impedance of the filter measured at frequency f. Whatever the impedance of any other connected to the input or output lines Devices, provided that these other devices do not have a negative conductance, which is in the Practice is most unlikely. The one used before

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The term "short-circuit conductance" denotes the

Jl.

output terminals of the blocking circuit from conductance measured into the filter with short-circuited input terminals. The term "coupling resistance" or "üTDertragungsirapedanz", also used, relates to the ratio of V _T / I _O r, j where I _a -, the current flowing through a short-circuit connection of the blocking circuit during a further measurement, and Vj a is the voltage applied to the input terminals of the filter.

The invention will now be explained with reference to the accompanying drawings on the basis of several preferred embodiments described in detail, for example. iis represent:

Figure Λ a circuit diagram of an invention

according to the blocking circle,

Figure 2 is a switching scheme of a abge

converted embodiment of the trap circuit according to the invention,

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Figure 3 shows a similar diagram of another

maize modified embodiment of the trap circuit according to the invention and

Figure 4 is a perspective scheme

a practical Ausführungsforra of the erfindungsgernäße Trap circuit according to Figure 1 of the Drawings.

In Figure 1 of the drawings, a ¹ T-member low-pass filter with inductive series V / Eigen and a love ens chi uE capacitance 20 is shown, which the latter forms the stem of the T-member. With regard to the noise or interference signals to be suppressed, connections 1 and 2 are the input connections and connections 3 and 4 are output connections. Connections 2 and 4 are approximately at ground potential and are directly connected to one another. The series branch of the (D element v / ird is formed by mutually identical inductances L, which are connected in series between the connections 1 and J. On the filter side facing away from the noise source or the

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The pilter output side is a resistor to the inductance L. R connected in parallel. The optimal value of the resistance R is equal to the value of the characteristic impedance / L / C of the filter, although this value is not decisive and the filter will still have any interference sufficiently suppressed when the resistance value R of this optimal V / ert by the factor two or more deviates. If the V / id initial value R is ten times as large or ten times as small as the optimal value, so can the mode of operation of the filter can just be regarded as sufficient. This filter becomes signal frequencies allow less than 1/2 f to pass with little attenuation and try to block signal frequencies of more than 2 f, where "is the frequency

tiZ

FIG. 2 of the drawings shows a filter with two T-members connected in series, as shown in FIG of the drawings are shown. The connected to the connections 1

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dd

and 2 connected, ie close to the noise .bzw, not shown. The T-element located at the source of interference has the items L-, 2C ^ and R ^ in the same arrangement as in FIG. 1 of the drawings. The one connected to the connections 3 and 4, ie »the one from the noise or. T-link remote from the source of interference has the individual parts Lp, 2C ₂ and R ₂ in the same arrangement. The two T- members preferably have the same wave resistance, but different cut-off frequencies. Characteristic values of the individual parts are:

L ₁ - 30 / ίΗ, 2C ₁ = 0 a .6 M ^L 2 = 2 / tH, 2C ₂ * = 0 .04 y * R ₁ " ^R 2 - 10 pounds 1

The cut-off frequencies of the two T-links are included etv / e 53 IcHz or 800 kHz.

In Figure 3 of the drawings is a symmetric chain-like Tiefpe.ß-filter circuit with the Eingangsanschl'issen 1 and 2, the off norsiiischlussen ^ 3 and U- soräe a series inductor with inductance L and two laterally thereto arranged ITebenschluß-

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ι ο ^ ι y ο ι

capacities O shown. To the side of these two capacity branches two end members are arranged, each of which consists of one, an inductance L / 2 and one for this purpose, resistor R connected in parallel consist of a composite series impedance. Attenuate such filters interfering signals in every direction. However, better interference suppression is achieved if each Noise or interference source has a trap circuit, as shown in Figure 2 of the drawings.

The terms "entrance" and "exit" used above relate to the direction of propagation the noise or interference signals. The according to the invention However, filters can also be switched on in lines that carry the supply or signal current in the in the opposite direction, i.e. from connections and 4 to connections 1 and 2 of the filter. This is for the effect of the filters on the noise and Interfering signals of no concern.

Referring to Figure 4 of the drawings, there is a practical embodiment of the trap circuit according to the invention shown in Figure 1 of the drawings, which consists of

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an induction coil 5 arranged in a pot core 6, a capacitance 7, one inside a further pot core 9 arranged further induction coil 8 and one to this induction coil 8 connected in parallel Resistance 10 exists. The reference numerals 1 to 4 denote the input and output connections of the filter. The filter should be designed in this way when in use be that the source of the noise or interference to be suppressed with that of the induction coil 8 and the Resistor 10 is connected to the abelsgenen end. The capacity 7 v / e is the usual, overlapping coatings within a barium titanate dielectric in a known manner on. The pot cores 6 and 7 are also of a known type and consist of ferrite material. Of the Pot core 9 consists of conductive ferrite material, which has a dissipative effect on radio frequencies. The induction coil 8 has its own shunt conductance on, which results in a reliable interference blocking effect even if the over the Resistance 10 running branch was opened or unintentionally interrupted. Resistance 10 is

designed in such a way that it encompasses the entire frequency range to be suppressed, down to relatively

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lower frequencies at which the material of the pot core 9 is no longer sufficiently dissipative to achieve the desired blocking effect. The resistance value of the resistor 10 is in the range between > / L / G and 2 / L / C, L being the inductance of the induction coil 8 and 20 arranged in the pot core 9, the value of the capacitance 7. The entire arrangement shown in Figure 2 of the drawings is preferably built into a terminal box, not shown, which the latter protects the arrangement mechanically and electrostatically and electromagnetically shields.

The embodiments described above and shown in the drawing are embodiments of the invention only examples from which the person skilled in the art can now derive further embodiments according to the invention. So can the filters described above, for example, tripartite or also arbitrarily mehroliedri ^ and arbitrarily in connection with other known filter circuits be combined. Such forms of execution -.as also the filters are shown in Figures 2 and 3 of the drawings can by adding further links to one of the in Figure 4 of the drawings shown embodiment get extended"

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Claims (3)

Claims 1. Trap circuit in the form of a low-pass filter, in which at least one end element has an inductive series impedance is, characterized in that the admittance of the inductive series impedance has an effective conductance component of at least the same order of magnitude as the reciprocal of the filter characteristic impedance. 2o blocking circuit according to claim 1, characterized in that that the »conductivity value is in the range between half and twice the value of the reciprocal value of the filter wave resistance it lies. 3. Trap circuit according to claim 1 or 2 in conjunction with T-member low-pass filters, which two inductive series impedance and ice base member have an IT shunt capacitance, characterized in that the IJebenschlußverbindungen a capacity of 20 uF and one of the inductive series inpecknzen an impedance of im essential ^ liich the Scl: a; viderst ^r nd an inductance of L / tH, to v / elclier a * .7i-3 position R of p ^ rrrllel is connected (Figures 1 and 2). 009816/0571 4 ·. Trap circuit according to claim 1 or 2 in application to chain-shaped low-pass Si eb circuits, which have at least one series inductance, at least two lift-terminal capacitances and an inductive series impedance as end links, characterized in that the inductive inductance has an inductance of L // H, the capacitances have a size of C / tF and the inductive series impedances of the end members each have an impedance essentially equal to the impedance of an inductance of 1/2 L ^ H, to which a v / resistance R of i / It / GiTh is connected in parallel is (Figure 3) - 17 - BAD CRiGiNAL 009816/0571